Days of Ground Frost – Annual Average
The number of days with ground frost occurring is largely influenced by coastal temperatures.  Ground frost mostly (but not exclusively) occurs during winter, and during these months the sea temperature regulates the air temperature due to its latent heat properties.  The sea takes longer to heat up and cool down than the land, so the sea is still relatively warm from the summer temperatures and this influences land temperature close to the coast.  Inland the number of frost days is considerably greater, and increases with altitude to peak in the uplands.